Multilayer optical disc having a recording stack type indicator

ABSTRACT

A multilayer record carrier of a writable type has a first recording layer ( 40 ) having a first recording stack ( 50,51 ) of a first type and a second recording layer ( 41 ) having a second recording stack ( 54,55 ) of a second type. The first and second recording stacks have different writing parameters. Each recording layer has a pre-formed recording control pattern that is readable via a laser beam for indicating the track. At least one recording control pattern comprises a recording stack type indicator for indicating the writing parameters of the second recording stack. A recording device has a control unit ( 20 ) for adjusting recording parameters in the device in dependence of the recording stack type indicator retrieved from the recording control pattern.

The invention relates to a record carrier of a writable type forrecording information by writing marks in a track.

The invention further relates to a device for recording the recordcarrier.

A multilayer optical recording medium is known from Japanese PatentApplication JP-11066622. Each layer is provided with a stack ofmaterials that is sensitive to a laser beam for writing marks and(partially) reflects the beam for reading. Recently the DigitalVersatile Disk (DVD) has gained market share as a medium with a muchhigher data storage capacity than the CD. Presently, this format isavailable in a read only (ROM), recordable (R) and a rewritable (RW)version. For recordable and rewritable DVD, there are at present severalcompeting formats: DVD+R, DVD-R for recordable and DVD+RW, DVD-RW,DVD-RAM for rewritable. An issue for both the recordable and rewritableDVD formats is the limited capacity and therefore recording time becauseonly single-stacked media are present with a maximum capacity of 4.7 GB.Note that for DVD-Video, which is a ROM disk, dual layer media with 8.5GB capacity, often referred to as DVD-9, already have a considerablemarket share. However, it has become clear that a (re)writable fullycompatible dual-layer disk (e.g. dual-layer DVD+RW), i.e. within thereflection and modulation specification of the dual-layer DVD-ROM, isdifficult to achieve and therefore parameters of the writing-process andtracking signals of the recording stack may differ for various types ofstacks on different layers. A problem is that the properties of thestack require an adaptation of the recording process in a recordingdevice.

Therefore it is an object of the invention to provide a record carrierand a recording device wherein the recording process is adapted to therecording stack.

According to a first aspect of the invention the object is achieved witha record carrier of a writable type for recording information by writingmarks in a track via a beam of radiation entering through an entranceface of the record carrier, the record carrier comprising at least afirst recording layer having a first recording stack of a first type anda second recording layer having a second recording stack of a secondtype, the first recording layer being present at a position closer tothe entrance face than the second recording layer and the first andsecond recording stack having different writing parameters, and at leastone transparent spacer layer between the recording layers, eachrecording layer comprising a pre-formed recording control pattern thatis readable via said beam for indicating the track, and at least onerecording control pattern comprising a recording stack type indicatorfor indicating the writing parameters of the second recording stack.

According to a second aspect of the invention the object is achievedwith a device for recording the above record carrier by writing marks ina track via a beam of radiation, the device comprising a head forproviding the beam, a front-end unit for generating at least onescanning signal for detecting marks in the track and for detecting thepre-formed recording control pattern, and a demodulation unit forretrieving the recording stack type indicator from the scanning signal,and a control unit for adjusting recording parameters in the device independence of the recording stack type indicator retrieved from thescanning signal.

The effect of the measures is that the recording process is adapted tothe recording stack due to the type of recording stack being detectablefrom the pre-formed recording control pattern.

The invention is also based on the following recognition. Compatibilitywith existing standards for read-only type record carrier like DVD-ROMrequires predefined properties of both layers in a recorded disc. Inaddition to a dual-layer DVD+RW, it has been proposed to use dye-baseddual-layer DVD+R media which can have reflection and modulation valuesin accordance with the dual-layer DVD-ROM standard. For fabrication ofdual-layer DVD+R and dual-layer DVD+RW two processes are possible. In afirst process a first recording layer L0 is fabricated on a firsttransparent substrate containing pregrooves. On top of L0 a transparentspacer is placed in which grooves are present, or replicated. A secondrecording L1 layer is fabricated on top of the grooved spacer layer andthe disc is finished by applying a dummy substrate to the back of thesecond recording layer L1. In a second process a first recording layerL0 is fabricated on a first transparent substrate containing pregrooves.A second recording layer L1 is fabricated on a second substratecontaining pregrooves. The disc is finished by attaching the twosubstrates containing L0 and L1 to each other with a transparent spacerlayer in between. The physical structure of the L1 recording layerdiffers significantly for the two fabrication methods. Even a thirdfabrication process is possible in which L0 is build on top of L1 (bothlayers will be of the inverted stack type). Hence the parameters of therecording layers, e.g. the writing-process and tracking signals of theL1 recording stack, may differ for various types of stacks. Inparticular the inventors have seen that differences for the unrecordedlayers may exist due to the type of the recording stack that may(partly) disappear after recording. By making the type of recordingstack known to the recording device in advance the recording process canimmediately be optimized for the recording stack of the record carrierinserted in the device.

In an embodiment of the record carrier the recording control pattern ofthe first recording layer comprises a recording stack type indicator forindicating the writing parameters of the second recording stack. Thishas the effect that the recording stack type indicator for the secondlayer can be retrieved from the first layer. Advantageously the firstlayer can always be easily read because it is located closest to theentry side of the laser beam. Moreover variation of stack type is mostlikely in the lower layers, while the first layer for different brandsof recordable discs is expected to be less varying, e.g. comparable tosingle layer discs.

Further preferred embodiments of the device according to the inventionare given in the further claims.

These and other aspects of the invention will be apparent from andelucidated further with reference to the embodiments described by way ofexample in the following description and with reference to theaccompanying drawings, in which

FIG. 1 a shows a disc-shaped record carrier (top view),

FIG. 1 b shows a cross-section taken of the record carrier,

FIG. 1 c shows an example of a wobble of the track,

FIG. 2 shows a recording device for adapting the recording process tothe stack type of a record carrier,

FIG. 3 shows a multilayer optical disc,

FIG. 4 a shows a multilayer having a recording stack of a conventionaltype,

FIG. 4 b shows a multilayer having a recording stack of an invertedtype,

FIG. 5 a shows a push-pull signal on recorded and unrecorded parts of aconventional stack,

FIG. 5 b shows a push-pull signal on recorded and unrecorded parts of aninverted stack,

FIG. 6 shows ADIP information in wobble modulation, and

FIG. 7 shows a wobble demodulation unit.

In the Figures, elements which correspond to elements already describedhave the same reference numerals.

FIG. 1 a shows a disc-shaped record Carrier 11 having a track 9 and acentral hole 10. The track 9 is arranged in accordance with a spiralpattern of turns constituting substantially parallel tracks on aninformation layer. The record carrier may be an optical disc having aninformation layer of a recordable type. Examples of a recordable discare the CD-R and CD-RW, and the DVD+RW. The track 9 on the recordabletype of record carrier is indicated by a pre-embossed track structureprovided during manufacture of the blank record carrier, for example apregroove. Recorded information is represented on the information layerby optically detectable marks recorded along the track. The marks areconstituted by variations of a first physical parameter and thereby havedifferent optical properties than their surroundings. The marks aredetectable by variations in the reflected beam, e.g. variations inreflection.

FIG. 1 b is a cross-section taken along the line b-b of the recordcarrier 11 of the recordable type, in which a transparent substrate 15is provided with a recording layer 16 and a protective layer 17. Thetrack structure is constituted, for example, by a pregroove 14 whichenables a read/write head to follow the track 9 during scanning. Thepregroove 14 may be implemented as an indentation or an elevation, ormay consist of a material having a different optical property than thematerial of the pregroove. The pregroove enables a read/write head tofollow the track 9 during scanning. A track structure may also be formedby regularly spread sub-tracks which periodically cause servo signals tooccur. The record carrier may be intended to carry real-timeinformation, for example video or audio information, or otherinformation, such as computer data.

FIG. 1 c shows an example of a wobble of the track. The Figure shows aperiodic variation of the lateral position of the track, also calledwobble. The variations cause an additional signal to arise in auxiliarydetectors, e.g. in the push-pull channel generated by partial detectorsin the central spot in a head of a scanning device. The wobble is, forexample, frequency modulated and position information is encoded in themodulation. A comprehensive description of the prior art wobble as shownin FIG. 1 c in a writable CD system comprising disc information encodedin such a manner can be found in U.S. Pat. No. 4,901,300 (PHN 12.398)and U.S. Pat. No. 5,187,699 (PHQ 88.002). The wobble modulation is usedto encode physical addresses, for example in DVD+RW as shown in FIG. 6,while wobble demodulation is shown in FIG. 7.

User data can be recorded on the record carrier by marks having discretelengths in unit called channel bits, for example according to the CD orDVD channel coding scheme. The marks are having lengths corresponding toan integer number of channel bit lengths T. The shortest marks that areused have a length of a predefined minimum number d of channel bitlengths T for being detectable via the scanning spot on the track thathas an effective diameter, usually being roughly equal to the length ofthe shortest mark.

According to the invention the record carrier is a multilayer recordcarrier, and each recording layer comprises a pre-formed recordingcontrol pattern that is readable via a scanning beam for indicating thetrack. At least one of the recording control patterns comprises arecording stack type indicator for indicating the writing parameters ofthe second recording stack as discussed in detail with reference toFIGS. 4 and 5. The recording control pattern may be constituted by apregroove having a wobble modulation encoding the recording stack typeindicator. The encoded stack type indicator is schematically indicatedby area 12 in FIG. 1 a. It is to be noted that in practicalcircumstances recording control information including the stack typeindicator will be encoded using a multitude of windings of the track,i.e. the area being encoded constituting an annular shaped area Thestack type indicator may be constituted by a small number of bits onlyindicating one of a few types, or it may include a substantial list ofparameters for the recording process and recording strategy. In anembodiment the recording control information is recorded repeatedly,i.e. the area having the wobble modulation contains a multitude ofcopies of the stack type indicator.

FIG. 2 shows a recording device for adapting the recording process tothe stack type of a record carrier. The device is provided with meansfor scanning a track on a record carrier 11 which means include a driveunit 21 for rotating the record carrier 11, a head 22, a servo unit 25for positioning the head 22 on the track, and a control unit 20. Thehead 22 comprises an optical system of a known type for generating aradiation beam 24 guided through optical elements focused to a radiationspot 23 on a track of the information layer of the record carrier. Theradiation beam 24 is generated by a radiation source, e.g. a laserdiode. The head further comprises (not shown) a focusing actuator formoving the focus of the radiation beam 24 along the optical axis of saidbeam and a tracking actuator for fine positioning of the spot 23 in aradial direction on the center of the track. The tracking actuator maycomprise coils for radially moving an optical element or mayalternatively be arranged for changing the angle of a reflectingelement. The focusing and tracking actuators are driven by actuatorsignals from the servo unit 25. For reading the radiation reflected bythe information layer is detected by a detector of a usual type, e.g. afour-quadrant diode, in the head 22 for generating detector signalscoupled to a front-end unit 31 for generating various scanning signals,including a main scanning signal 33 and error signals 35 for trackingand focusing. The error signals 35 are coupled to the servo unit 25 forcontrolling said tracking and focusing actuators. The error signals 35are also coupled to a demodulation unit 32 for retrieving the physicaladdresses and recording control information including the stack typeindicator from the preformed recording control pattern such as wobblemodulation. A detailed embodiment of wobble modulation detection isgiven in FIG. 7. The main scanning signal 33 is processed by readprocessing unit 30 of a usual type including a demodulator, deformatterand output unit to retrieve the information.

The device is provided with recording means for recording information ona record carrier of a writable or re-writable type, for example CD-R orCD-RW, or DVD+RW or BD. The recording means cooperate with the head 22and front-end unit 31 for generating a write beam of radiation, andcomprise write processing means for processing the input information togenerate a write signal to drive the head 22, which write processingmeans comprise an input unit 27, a formatter 28 and a modulator 29. Forwriting information the beam of radiation is controlled to createoptically detectable marks in the recording layer. The marks may be inany optically readable form, e.g. in the form of areas with a reflectioncoefficient different from their surroundings, obtained when recordingin materials such as dye, alloy or phase change material, or in the formof areas with a direction of polarization different from theirsurroundings, obtained when recording in magneto-optical material.

Writing and reading of information for recording on optical disks andformatting, error correcting and channel coding rules are well-known inthe art, e.g. from the CD or DVD system. In an embodiment the input unit27 comprises compression means for input signals such as analog audioand/or video, or digital uncompressed audio/video. Suitable compressionmeans are described for video in the MPEG standards, MPEG-1 is definedin ISO/IEC 11172 and MPEG-2 is defined in ISO/IEC 13818. The inputsignal may alternatively be already encoded according to such standards.

The control unit 20 controls the scanning and retrieving of informationand may be arranged for receiving commands from a user or from a hostcomputer. The control unit 20 is connected via control lines 26, e.g. asystem bus, to the other units in the device. The control unit 20comprises control circuitry, for example a microprocessor, a programmemory and interfaces for performing the procedures and functions asdescribed below. The control unit 20 may also be implemented as a statemachine in logic circuits. The control unit performs the functions ofretrieving the stack type indicator and adjusting the recordingparameters in the device in dependence of the recording stack typeindicator retrieved. In particular the control unit may be arranged foradjusting as recording parameters gain or polarity settings of the servounit 25, or for adjusting as recording parameters a write strategy or apower control procedure for recording data on the second recordinglayer.

FIG. 3 shows a multilayer optical disc. L0 is a first recording layer 40and L1 is a second recording layer 41. A first transparent layer 43covers the first recording layer, a transparent spacer layer 42separates both recording layers 40,41 and a substrate layer 44 is shownbelow the second recording layer 41. The first recording layer 40 islocated at a position closer to an entrance face 47 of the recordcarrier than the second recording layer 41. A laser beam is shown in afirst state 45 focused on the L0 layer and the laser beam is shown in asecond state 46 focused at the L1 layer. Each recording layer has thepre-formed recording control pattern that encodes the recording stacktype indicator, for example encoded by the wobble modulation of thepregroove.

Multilayer discs are already available as read-only pre-recorded discs,such as DVD-ROM or DVD-Video. A dual layer DVD+R disc has recently beensuggested, which disc should preferably be compatible with the duallayer DVD-ROM standard. The reflection levels of both layers are >18%.The L0 layer has a transmission around 50-70%. A spacer layer separatesthe layers with a typical thickness between 30 and 60 μm. The L1 layerhas a high reflection and needs to be very sensitive. Also rewritabledual-layer discs are proposed. The L0 layer has a transmission around40-60%. The effective reflection of both layers is typically 7% althoughlower and higher values are possible (3%-18%).

The two information-storage layers that are present in a dual-layer discwill, in general, have different physical characteristics. An obviousdifference between the two layers is the reflection and transmission. Inorder to be able to access the deeper layer L1, the upper layer L0should be sufficiently transparent at the laser wavelength. Also, toobtain sufficient read-out signals from the deeper layer L1, this layershould be highly reflecting at the laser wavelength. Other physicaldifferences can be stack structure (inverted or conventional), groovedepth, stack design, etc. A consequence of the different physicalproperties of L0 and L1 is that important parameters that should beknown to the drive—e.g. write-strategy (type or parameters), indicativewrite power, target β, etc—will; in general, be different for the twolayers. The parameters need to be known to a drive to ensure properrecording performance, disc handling, etc. Due to the requiredcompatibility with existing read-only standardized record carriers, likethe DVD-ROM standard, for a DVD-type dual-layer recordable (orrewritable) disc there are two options possible for the layout of thedisc. These two options are referred to as ‘parallel track path’ (PTP)and ‘opposite track path’ (OTP), which indicates the direction of thespiral in both layers. In PTP discs there is one information zone perlayer (two in total), while in OTP discs there is one information zoneextending over the two layers.

To manufacture a recordable dual layer DVD, there are two basic optionsfor the disc design. In both cases a first substrate with a firstsemi-transparent recording stack L0 is manufactured in a conventionalway: spin-coating of the dye-layer on a pre-grooved 0.575 mm thicksubstrate followed by (sputter) deposition of a semi-transparent mirror(e.g. dielectric layer(s), thin metal layer, or a combination). For thesecond recording stack on recording layer L1 there are twopossibilities, as illustrated by FIG. 4. It is noted that writable andrewritable optical storage media having other layer thicknesses and/or 3or more recording layers can be produced in a similar way.

FIG. 4 a shows a multilayer having a recording stack of a conventionaltype. A first L0 recording layer 40 has a recording material 50 in apregroove pattern provided in an upper substrate. The direction of thelaser beam entering the record carrier is indicated by arrow 49. Areflecting layer 51 is applied on the recording material 50. On top ofthe first recording layer L0, a transparent spacer-layer 42 is applied(e.g. spin-coat or PSA). The spacer layer 42 either already containspre-grooves for the L1 recording layer, or pre-grooves for the L1recording layer are mastered into the spacer after application to L0(e.g. using 2P replication). On this pre-grooved spacer, the L1recording layer is applied: a second recording material 52, e.g.spin-coating a dye, followed by a mirror material 53, e.g. (sputter)deposition of a metallic mirror. The stack deposited in this order isusually called conventional. Finally, a 0.575 mm thick dummy substrate(no grooves) is bonded to the L1 layer using e.g. the same technology asused for bonding single-layer DVD+R discs.

FIG. 4 b shows a multilayer having a recording stack of an invertedtype. A first L0 recording layer 40 and spacer 42 are provided as inFIG. 4 a. A recording stack L1 is deposited on a separate substratecontaining pre-grooves. First a reflecting material 55 is applied on thepre-grooves, and then a recording material 54 is deposited. In this case(referred to as inverted stack), the individual layers of the recordingstack are deposited in inverse order compared to a conventional stack inFIG. 4 a. The second substrate is then combined with the substratecontaining the L0 stack to form the dual layer disc. A spacer layer 42separates L0 and L1.

Since conventional and inverted stacks are different from atechnological point of view they also differ in their recordingparameters. These differences are especially apparent in the case of arecordable disc based on a spin-coated dye layer due to the effect ofleveling, i.e. different layer thickness in the grooves and on thelands. An example is the push-pull signal (PP) for the radial error.

FIG. 5 a shows a push-pull signal on recorded and unrecorded parts of aconventional stack. An upper curve displays the HF read signal 56, thefirst part (time 0-4 msec) showing signal values due to written data,the second part showing almost zero signal values due to an unrecordedpart of the track. A lower curve shows the push-pull signal 57, i.e. asine wave of which the amplitude is smaller for the unrecorded part.

FIG. 5 b shows a push-pull signal on recorded and unrecorded parts of aninverted stack. An upper curve displays the HF read signal 58, the firstpart (time 0-5 msec) showing signal values due to written data, thesecond part showing almost zero signal values due to an unrecorded partof the track. A lower curve shows the push-pull signal 59, which haslower amplitude than the push-pull signal 57 for the conventional stackin FIG. 5 a. Moreover the amplitude is larger for the unrecorded part.

Another difference between stack types is the polarity of the push-pullsignal in case of inverted type L1 layers. Both on-groove andin-between-groove recording are possible, which have oppositePP-polarity. It is noted that for a conventional stack only on-grooverecording is possible. Also further recording parameters, like writingpower or writing pulse waveform, are different for different stacktypes. The different characteristics can be problematic in the handlingof the discs in optical drives. For example, drives developed forrecording of dual layer discs of conventional stack type may fail due todifferent behaviour of a disc of inverted stack type. Note that bothtypes could still be designed in such a way that they are according tothe DVD specifications after recording but differences might occurbefore or during recording.

The solution is to indicate the stack type of the second recording layerL1 in the disc. The type can be conventional stack or inverted stack.Other stack types may be defined also. The information on the stack typecan be included in e.g. the ADIP information of the wobbled pre-groove(as shown in FIG. 6) or by other means to store the information(headers, embossed data). By introducing such a distinction of stacktype in the disc, the parameter ranges defined in the standard can beadapted for each stack-type. Consequently, also optical disc drives canadapt their settings to the L1-type. For example, (gain or polarity)settings of the radial servo and the wobble detection can be adapted tothe different amplitudes of the push-pull signal of the stack types.Another possibility is to adapt the write strategy or the optimum powercontrol (OPC) procedure to record data according to the specificL1-type.

It is preferable to include the type indication of L1 not only in theL1-layer itself but in the L0-layer as well. The L0 layer is usually aconventional stack and information in this layer can therefore be readwithout complications under all circumstances. Moreover, the L0 layer iscloser to the entrance surface and will probably be accessed andrecorded first in a typical drive. By including the L1 stack-typeindication already in L0, the drive can already adapt its settingsbefore accessing L1 avoiding all possible problems related to theL1-type.

FIG. 6 shows ADIP information in wobble modulation. The wobblemodulation encodes additional information that is called Address InPregroove (ADIP) in the DVD+RW system. Each ADIP bit 65 is constitutedby ADIP bit sync (one wobble period 64 corresponding to 32 channelbits), followed by a ADIP word sync field (3 wobble periods) and theADIP Data-bit field of 4 wobble periods, followed finally by 85 monotone(i.e. not modulated) wobble periods. The Figure shows a first wobble 61which is encoded as an ADIP word sync, in which the word sync field hasinverted wobbles and the data-bit field has non modulated wobbles.Second wobble 62 encode a data bit value 0 and third wobble 63 encodes adata bit of value 1.

In an embodiment (e.g. for dual-layer DVD+R) the stack-type indicationis included in the physical format information in the ADIP in theLead-in Zone. Byte 2 of the ADIP describes the disc structure. Bit b7and bit b3 of this Byte 2 can be used. Either of these two bits can beused for the L1-type indication (bit b4 is also free in single layerDVD+R but may be used for indicating the track path PTP vs. OTP). Thispart of the ADIP information will be identical in both layers, thus theinformation on L1-type is already available when only reading from L0.

FIG. 7 shows a wobble demodulation unit. The input unit 71 provides apush-pull signal derived from the head scanning the track. A filter 72filters the signal by high pass and low pass filters for isolating thewobble frequency and generating a wobble signal. A phase locked loop 73is locked to the wobble frequency, and generates via a 32×multiplier 75the synchronous write clock for recording marks in units of channelbits. A synchronous wobble unit 74 provides a wobble clock period tomultiplier 76 which also receives the wobble signal. The output of themultiplier 76 is integrated in integrate and dump unit 77, of which theoutput is samples via a sample switch to a sync threshold detector 78coupled to a ADIP bit synchronizer that detects the ADIP bit syncs. Asecond multiplier 81 is provided with a 4 wobble period signal havingtwo inverted and two non inverted wobbles and the wobble signal on asecond input for synchronous detection over 4 wobble periods. A secondintegrate and dump unit 82 integrates output signal of the multiplier82, while a bit value threshold detector 83 for detecting the values ofthe encoded bits.

Although the invention has been mainly explained by embodiments usingoptical discs based on change of reflection, the invention is alsosuitable for other record carriers such as rectangular optical cards,magneto-optical discs or any other type of information storage systemthat has a pre-applied pattern on a writable record carrier. It isnoted, that in this document the word ‘comprising’ does not exclude thepresence of other elements or steps than those listed and the word ‘a’or ‘an’ preceding an element does not exclude the presence of aplurality of such elements, that any reference signs do not limit thescope of the claims, that the invention may be implemented by means ofboth hardware and software, and that several ‘means’ or ‘units’ may berepresented by the same item of hardware or software. Further, the scopeof the invention is not limited to the embodiments, and the inventionlies in each and every novel feature or combination of featuresdescribed above.

1. Record carrier of a writable type for recording information bywriting marks in a track via a beam of radiation entering through anentrance face of the record carrier, the record carrier comprising atleast a first recording layer (40) having a first recording stack of afirst type and a second recording layer (41) having a second recordingstack of a second type, the first recording layer being present at aposition closer to the entrance face than the second recording layer andthe first and second recording stack having different writingparameters, and at least one transparent spacer layer between therecording layers, each recording layer comprising a pre-formed recordingcontrol pattern that is readable via said beam for indicating the track,and at least one recording control pattern comprising a recording stacktype indicator for indicating the writing parameters of the secondrecording stack.
 2. Record carrier as claimed in claim 1, wherein therecording control pattern of the first recording layer comprises arecording stack type indicator for indicating the writing parameters ofthe first recording stack, and the recording control pattern of thesecond recording layer comprises the recording stack type indicator forindicating the writing parameters of the second recording stack. 3.Record carrier as claimed in claim 1, wherein the recording controlpattern of the first recording layer comprises a recording stack typeindicator for indicating the writing parameters of the second recordingstack.
 4. Record carrier as claimed in claim 1, wherein the recordingcontrol pattern comprises a recording stack type indicator that is anindicator of a polarity of a push-pull signal to be used for scanningthe track.
 5. Record carrier as claimed in claim 1, wherein thepre-formed recording control pattern is constituted by a pregrooveindicating the position of the track, the pregroove exhibiting a wobbleconstituted by displacements of the pregroove in a direction transverseto the longitudinal direction of the track, and the wobble exhibiting amodulation representing the recording stack type indicator.
 6. Devicefor recording a record carrier (11) by writing marks in a track via abeam of radiation (24), the record carrier comprising at least a firstrecording layer (40) having a first recording stack of a first type anda second recording layer (41) having a second recording stack of asecond type, the first recording layer being present at a positioncloser to the entrance face than the second recording layer and thefirst and second recording stack having different writing parameters,and at least one transparent spacer layer between the recording layers,each recording layer comprising a pre-formed recording control patternthat is readable via said beam for indicating the track, and at leastone recording control pattern comprising a recording stack typeindicator for indicating the writing parameters of the second recordingstack, the device comprising a head (22) for providing the beam, afront-end unit (31) for generating at least one scanning signal (33, 35)for detecting marks in the track and for detecting the pre-formedrecording control pattern, and a demodulation unit (32) for retrievingthe recording stack type indicator from the scanning signal, and acontrol unit (20) for adjusting recording parameters in the device independence of the recording stack type indicator retrieved from thescanning signal.
 7. Device as claimed in claim 5, wherein the controlunit is arranged for adjusting as recording parameters gain or polaritysettings of a radial servo unit (25).
 8. Device as claimed in claim 5,wherein the control unit is arranged for adjusting as recordingparameters a write strategy or a power control procedure for recordingdata on the second recording layer.